Means and method of surveying wells



G. E. NEVILL MEANS ANDl METHOD' OF SURVEYING WELLS Feb. 13, 194s.`

original Filed March 18, 1935 INVENTOR BY M ATTORNEYS Feb. i3, i y 2,369,403

Gale E. Nevill, San Antonio, Tex., signor to .um v. inclinata',4 Montebello, c sur. continuation n: application seria No. 11,594, r

umn 1s, 193s. rms-application octobesn. t

me, serai Naisam 1 claim. (ci. as -ztsi 'The invention relates to well surveying inskilled in the nrt when the following descripstruments and in particular to devices adapted tion 4is read in connection with the accompanyto determine and record the amount and direcj ing drawing, wherein: tion of the inclination of well bores. Fig. l-is a side view, partially in sectiocn, show- This application is a continuationof applica- 5 ing a core bit and a dummy retrievable core tion Serial No. 11,694, filed March 18, 1935 on barrel seated therein and embodying features i of Gale E. Nevill, and entitled Means of the invention?r method of surveyins wells.

Dimculty has been experienced in obtaining r"accurate compass bearing'.` of readings of well inclination where r, magnetic compass is employed and the device Vis run inside oi' a steel pipef o r 'casing because of the magnetic interferenceotthe surrounding steel. This -dimculty kaatsen-avoided m some instancias by positionv=: ;..inf-fthefci'in'ipass type instrument within a speciali section of pipe of nom-'magnetic material, liu'i'f cost-and inability to dnd-such a materlal possessingV suitable physical properties were encountered. The magnetic interference risk of a cave-in of the walls ofthe well with Fig. 2 is a bottom view oi a core bit of the typeshownlnFig.1;and 10 Fig. 3 is a partially sectional view of the lower l5 Well has therein s. drill bit I6 adapted t0 drill `the well. The bit lB-is threadedly attached to a suitable drill collar l1, which in turn may be connected to a conventional rotatable drill pipe it, frequently 2o termed a wire line core bit, has a central axial may be overcome by running the compass instrument in an open or uncased hole, but the D .(not shown). The drill loit opening'or core inlet it, which may be best seen in Fil.4 2." The' blt has a core barrel seat, such fas Il, which is adapted to receive a retrievable the consequent loss ot the device is undesirable.

core'. barrel which maybe inserted downwardly' Furthermore, when a 4well'is being drilled by the u and removed upwardly through the drill collar rotary method the drill stem must lbe removed 4 Eanddrill pipe, which together constitute the drill f from the well to permit the use of a= magnetic l. Tstem., A perforated guide bushing, such as 2|,

surveying instrument in anv hole; may 'be placed in the drilllcollar to support the itis an obiectof the invention tn provide a upper end ot a'core Ibarrel in axially aligned whereby a compass type ,well surveying 0 position. o -instri'nnent may be lowered and vrasiedthrough15.k Instead oi the regular core barrel which is` fjtfiiefinside ot la steel drill pipe and extended inserted through the bushing 2i `and adapted to downwardly an opening in the drill bit'. engage the seat il so as toreeeive acore. there so that the compass will be spaced away from is here provideda dummy core barrel 22, which parte to avoid magnetic interference. may be its upper end with a suit- It is a further object ot the invention to progable dog-.or head-"123 adapted to heL engaged by vide directional survey instrument which fis. 'an overshot usually lowered on a wire 1ine. At tdilted 1dr 118 A dummy Wire une 20N barrel fitsJowenand the dummy oo re barrel is formed to belowered throush the drill `pipe and engage with l shoulder 24 adapted to engage and be thcnormalcore barrel seat, at the same time- QQ supported on the seat II oi.' the blt It Y a compass survey instrument down` f Attached te the. dummy barrel and formingfaj Wil'dly throuth the core Openinlnd Q ipart thereof is the extension, or downwardly exlllminlilyb, m08 0f the 10,16 blt to' vld' section 2|', which may be of brasaalumagnetic intrierence. hin'mnpor other nun-magnetic material. cav-1 'Itis another obiect of the invention to pro.4 ms@ y2|, formed near the lower end o! nicthod-oiobtainlns a directional suive! thefextenniendl, provides a 'suitable chamber -cfja well with a magnetic type instrument and nl whiehto locate' the instrument wlthout'thefneces'sltv-oi removing the drill-pipe -winch is indicated generally at n. `The from thewell bore. 'mnd plug seais thelower. end ofthecav r. r

, It is yet-another object-to seat 'a surveying in, ,M itx-3! mdfgnidestheemhly 'durinp its dawnstrumentin the core barrel seat so thatits- @ward the drill pipe. drilled-" .tionfintbedrillstemwill bekam-without the 1- n Imm! line 91' Simili! lmr The 2 3 118 Duim l These andfother objects and' advantag ot theme bymeans ,f the invention fwui be readily-apparaissaient it-ll' vwenttlt close proximity of steel or other magneticlmaterials will very probably result in erroneous data, and therefore in order to avoid the magnetic interference from the steel bit and associated parts the extension 26 is made sutllciently long so thatv the compass in the instrument is ad vancedvfar enough ahead of thebit tol be substantially free yfrom such interference.

A simple form of compass type surveying instrument suitable forl use with the invention is' that disclosed in -the`paterlt to Macgeorge, No. 270,597, Jan. 16, 1883. Of course, more elaborate forms of instruments employing magnetic orienting means may be employed without departing l, from the spirit of the invention.

' such long runs is quite important' as there is no drilling time lost in pulling the drill stem from the hole to replace the bit. It will be seen that it may be imperative to secure directional surveys of the vhole as the drilling progresses, and it is equally desirable to do this without performing the otherwise unnecessary operation of pulling the drill stem just to permit the use of an instrument in an open hole.

In the use of the present invention the survey is made with the regular core barrel removed from the bit and' drill stem. The bit is raised and suspended oi bottom a suilcient distance and the dummy barrel containing the survey apparatus is either lowered through thedrill stem until it comes to 'rest on the seat l9 with the extension allowed to protrudeV through the core opening to space the compass away from the bit. After the'magnetic bearing and amount of inclination of the well bore have been determined the apparatus is raised or retrieved for observation and inspection and the regular drilling routineisresumed.

The time required for this entire performance' will usually be less than an hour as compared to several hours required to make a round trip with the drill stem and bit. It will be seen that a directional survey is obtained with a simple central axial opening, of a core barrel seat formed in the opening, a guide spaced above said seat and axially aligned therewith, a dummy core barrel 'lowerable and removable through said drill stem, a shoulder on said dummy core barrel formed to engage said seat, said dummy core lbarrel being adapted to be supported in aligned position by said seat'and guide, -a section on said dummy core barrel extending downwardly therefrom and adapted to pass through the axial opening in said drill as said dummy core barrel is lowered into seated position, and a chamber in lsaid section adapted to hold a magnetic type directional well surveying instrument therein, said extension section being of non-magnetic material and adapted to space the compass oi the instrument a suillcient distance away fron the drill to substantially avoid magnetic interference.

2,. The combination with a drill stem `and a drilling tool of magnetic material attached to thelower end thereof having a central axial opening, of a core barrel seat aligned with the opening, a dummy core barrel adapted to be run throughsaid drill stemand formed to engage said seat, a ori-magnetic section on said dummy core barrel 4extending downwardly through the axial opening of said drilling tool and in advance thereof, and a chamber in said non-magnetic section formed to receive a directional surveying instrument including a compass and adapted to space the compass from said drilling tool whereby the compass is located beyond the magnetic ileld of said drilling tool substantially free from magnetic interference when the dummy barrel engages said seat.

3. The combination with a drill stem and a drilling tool of magnetic material attached to the 'lower end thereof and having a central axial opening, of a seat aligned with said opening and in spaced relation thereto, a dummy barrel adapted to be runin and out through said drill stem and formed to engage said seat, a nonmagnetic section on said dummy barrel, said sec tion being arranged to extend axially and downwardly through the axial `opening and in advance thereof when the barrel engages said seat, and a recess in said non-magnetic section formed to hold a directional survey instrument including a compass. said non-magnetic section being formed to space the compass of the surveying instrument beyond the magnetic ileld of the magnetic material of said drill stem and drilling tool when the dummy barrel is in seated position whereby magnetic directional surveys may be oba housing adapted to be run through said drill stem, an extension on said housing of non-magnetic material and formed to be extended downwardly through the opening in said drilling tool, a chamber in said extension adapted to hold a compass type directional well surveying instrument, and means to support the housing in aligned position whereby 'the compass of the' instrument is spaced below and away from the steel of said drill and associated .parts a suillcient distance to substantially avoid magnetic interference.

5. In combination, a tubular drill stem. a core forming drill thereon having an inlet for a core. a supporting seat in said drill, a housing lowerable through said drill stem and arranged to engage and be supported by said seat, a non-magnetic extension on said housing formed@ to extend through the opening insaid drill and in advance thereof 'when said housing is in seated position, said extension having a chamber adapted to contain a directional well surveying instrument including a compass, and adapted to space the compass a suillcient distance below and awayv from thesteel of said drill and associated parts A to substantially avoid magnetic interference.

6. In combination, a tubular drill stem, a dri1l mg tool attached to the lower end thereof and having an opening therethrough, a housing adapted .to be run in and out of the well through said drill stem, means for. limiting the downward movement ot said housing in said drill stem and drilling tool. a non-magnetic section on said housing, and an instrument recess in said nonlri'luneticoectioniox'nuadtolxolclaeon'masstime well instrument adapted U0 determigle l the amount'and.direction orwell deviation. said non-magnetic sejction'being formed-to locate the f aurveyyin instrinnent beyond the --x'nagnetic field of, and in advance of said-drilling tool when the housing visA in lowermost position, whereby the direction ol deviatlon'lnay be determined substantially free from interference due to magnetic material inthe and assoclatedlparts. L Apparatus of the character described compricing a Iwell tube formed of magnetic material and a support adjacent its lowerend.

t a'removabiehousing on the support andgformed with an'extension composed of non-magnetiche.-

4 terialrw'hich is extended beyondthefwell tube and which is provided with a chamber adapted VQ' to contain aV directional well surveying instrument includins'a compass,A said extension being of suoli length that the 'chamber located a vdis- 'tance from the adjacent end of the well tube Such that said surveying instrument will, when l0 in` operating position! be located beyond magnetic field o f thewell tube. Y

` Gam' E Nimm.. 

